Excavating device



Sept. 15, 1931. LORENZ 11,823,367

EXCAVATING DEVICE Filed Jan. 18, 1929 I -Fzg 2.

ave/liar:

Batented Sept. 15, 1931 UNITED STATES PATENT OFFICE EXCAVATING DEVICEApplication filed January 18, 1929, Serial No. 333,367, and in GermanyDecember 8, 1927.

My invention relates to a device for excavating the earth underneath abore-hole to produce a cavity of definite dimensions. By filling thiscavity with'concrete a socle or a '5 supporting base is produced of acertain defined size giving a sure support for the pile to be erectedwithin the bore-hole. The pile is thus enabled to carry a much greaterload than it has been hitherto possible, inasmuch In as the pressure ofthe supporting base on the ground can now be calculated and its limitsare known.

The primary feature of my device resides in the arrangement of resilientsteel knifeblades kept in' contracted position by their own resiliencyand adapted to be bent outwards by moving the holders of the bladesagainst each other while theyare working underneath the bore-hole.

Other objects of my invention and certain details of construction willbe apparent from the following description and the annexed drawings, inwhich .Figs. 1 and 2 show the new device in two different elevations. Ip I The enlarging boring device comprises two or more resilient steelknives s. The ends 0 I of the knives are articulated to the toot-plate wand to the head plate 1". The latter is fastened to the square bar awhile the plate w is fastened to the square tube '0. The bar it isguided within the pipe n so that the plates '41] and 9" may be movedagainst each other while they are simultaneously rotating. By

these means the knives are rotated in a reliable manner. A spider tkeeps the knives s apart at a distance greater than the distance oftheir articulation on the plates 0", w. When neath the bore-hole, and

path in order to exert a better grip on the earth.

What I claim is:

1. In a device for excavating the earth underneath a bore-hole,resilient steel knit'cblades kept in contracted position by their ownresiliency, two holders of the knife blades adapted to be moved at willrelatively to each other for bending the said knifeblades outwardlywhile being underneath the bore-hole, and pivotal connections betweenthe holders and the ends of the knife-blades.

2. In a device for excavating the earth underneath a bore-hole,resilient steel knifeblades kept in contracted position by their ownresiliency, two holders of the knifeblades not rotatable against eachother, but

adapted to be moved at will lengthwise relatively to each other forbending the said knife-blades outwardly while being underivotalconnections between the holders an the ends of the knife-blades.

3. In a device for excavating the earth underneath a bore-hole,resilient steel knifeblades kept in'contracted position by their ownresiliency, two holders of the knifeblad-es adapted to be moved at willrelatively to each other for bending the said knife blades outwardlywhile being underneath the bore-hole, pivotal connections between theholders and the ends of the knife-blades, and adjustable means on one ofthe said holders for limiting the relative movement of the holders.

In testimony whereof I affix my signature.

ERNST LORENZ.

